Background: The purpose of the study was to investigate the effects of the pregnane X receptor (PXR)*1B polymorphisms on CYP3A4 enzyme activity and postoperative fentanyl consumption in Chinese patients undergoing gynecological surgery.

Methods: A total of 287 females of Han ethnicity, aged 20 to 50&nbsp;years old, ASA I or II, scheduled to abdominal total hysterectomy or myomectomy under general anesthesia were enrolled. The analgesic model used was fentanyl consumption via patient-controlled intravenous analgesia (PCIA) in the post-operative period. Additionally, pain was assessed using a visual analog score (VAS). Pain scores, occurrence of adverse reactions and consumption of fentanyl were recorded during the 24&nbsp;h postoperative period. The enzyme activity of CYP3A4 was evaluated by measuring the plasma ratio of 1&prime;-hydroxymidazolam to midazolam 1&nbsp;h after intravenous administration of 0.1&nbsp;mg/kg midazolam. PXR genotyping was performed by direct DNA sequencing and the PXR*1B haplotype was analyzed via PHASE V.2.1 software.

Results: The polymorphism frequency of PXR11156A&thinsp;&gt;&thinsp;C/11193&nbsp;T&thinsp;&gt;&thinsp;C and 8055C&thinsp;&gt;&thinsp;T were 49.6 and 49.3%, and the rate of PXR*1B haplotype was 48.8% in our study. None of the pain scores, consumption of fentanyl 24&nbsp;h post-operatively or enzyme activity of CYP3A4, showed differences among different genotypes.

Conclusions: PXR11156A&thinsp;&gt;&thinsp;C, PXR11193T&thinsp;&gt;&thinsp;C, PXR8055C&thinsp;&gt;&thinsp;T or the PXR*1B haplotype do not appear to be important factors contributing to CYP3A4 activity and interindividual variations in postoperative fentanyl consumption in Han female patients undergoing gynecological surgery.

Trial registration: The DNA samples were obtained since 2007 to 2010&nbsp;year in our hospital, there was no registration at that time. So this section is not applicable to our research.

Background: The purpose of the study was to investigate the effects of the pregnane X receptor (PXR)*1B polymorphisms on CYP3A4 enzyme activity and postoperative fentanyl consumption in Chinese patients undergoing gynecological surgery.

Methods: A total of 287 females of Han ethnicity, aged 20 to 50&nbsp;years old, ASA I or II, scheduled to abdominal total hysterectomy or myomectomy under general anesthesia were enrolled. The analgesic model used was fentanyl consumption via patient-controlled intravenous analgesia (PCIA) in the post-operative period. Additionally, pain was assessed using a visual analog score (VAS). Pain scores, occurrence of adverse reactions and consumption of fentanyl were recorded during the 24&nbsp;h postoperative period. The enzyme activity of CYP3A4 was evaluated by measuring the plasma ratio of 1&prime;-hydroxymidazolam to midazolam 1&nbsp;h after intravenous administration of 0.1&nbsp;mg/kg midazolam. PXR genotyping was performed by direct DNA sequencing and the PXR*1B haplotype was analyzed via PHASE V.2.1 software.

Results: The polymorphism frequency of PXR11156A&thinsp;&gt;&thinsp;C/11193&nbsp;T&thinsp;&gt;&thinsp;C and 8055C&thinsp;&gt;&thinsp;T were 49.6 and 49.3%, and the rate of PXR*1B haplotype was 48.8% in our study. None of the pain scores, consumption of fentanyl 24&nbsp;h post-operatively or enzyme activity of CYP3A4, showed differences among different genotypes.

Conclusions: PXR11156A&thinsp;&gt;&thinsp;C, PXR11193T&thinsp;&gt;&thinsp;C, PXR8055C&thinsp;&gt;&thinsp;T or the PXR*1B haplotype do not appear to be important factors contributing to CYP3A4 activity and interindividual variations in postoperative fentanyl consumption in Han female patients undergoing gynecological surgery.

Trial registration: The DNA samples were obtained since 2007 to 2010&nbsp;year in our hospital, there was no registration at that time. So this section is not applicable to our research.